<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			body{
				margin: 0;
				padding: 0;
				background-color: #040D15;
			}
			a{
				position: absolute;
				left: 50%;
				top: 50%;
				transform: translate(-50%,-50%);
				width: 200px;
				height: 60px;
				text-align: center;
				line-height: 60px;
				color: #fff;
				font-size: 18px;
				text-transform: uppercase;
				text-decoration: none;
				border-radius: 40px;
				background: linear-gradient(90deg,#03a9f4,#f441a5,#ffeb3b,#03a9f4);
				background-size: 400%;
				z-index: 1;
				
			}
			a:hover{
				
			}
			@keyframes anima{
				from{background-position: 0%;}
				to{background-position: 400%;}
			}
			a::before{
				content: '';
				position: absolute;
				top: -5px;
				bottom: -5px;
				left: -5px;
				right: -5px;
				border-radius: 40px;
				background: linear-gradient(90deg,#03a9f4,#f441a5,#ffeb3b,#03a9f4);
				background-size: 400%;
				z-index: -1;
				opacity: 0;
				transition: 0.5s;
				
			}
			/* Filter 函数 */
			/* filter 属性定义了元素(通常是<img>)的可视效果(例如：模糊与饱和度)。 */
			/* blur(px)	给图像设置高斯模糊 */
			a:hover::before{
				filter: blur(20px);
				opacity: 1;
				animation: anima 8s linear infinite;
			}
			
		</style>
	</head>
	<body>
		<a href="#">button</a>
	</body>
</html>
